And they're off ... the 2018 Running of the Bulls

Participants run next to Fuente Ymbro fighting bulls on the fourth run of the San Fermin festival in Pamplona, Spain. (Jose Jordan / AFP/ Getty Images)

The small city of Pamplona in northern Spain is home every July to the running of the bulls, the highlight of the weeklong San Fermin festival.

The world-famous fiesta and its nine days and eight nights of traditional events, music and alcohol-soaked parties attract around 1 million visitors every year to the city of nearly 200,000.

Revelers run with Puerto de San Lorenzo's fighting bulls during the second day of the San Fermin Running of the Bulls festival in Pamplona, Spain. (Pablo Blazquez Dominguez / Getty Images) A reveler is tossed by a bull at the bullring during festivities of the San Fermin festival in Pamplona. (Ander Gillenea / AFP / Getty Images)

Left, revelers run with Puerto de San Lorenzo's fighting bulls during the second day of the San Fermin Running of the Bulls festival in Pamplona, Spain. Right, a reveler is tossed by a bull at the bullring in Pamplona. (Pablo Blazquez Dominguez / Ander Gillenea / AFP /Getty Images)

The San Fermin festival was immortalized by Ernest Hemingway in his 1926 novel, “The Sun Also Rises.”

For eight consecutive mornings starting Saturday, daredevils will race with bulls along a 930-yard street course to the city’s bullring, where the animals are killed during the traditional corridas.

Revelers protect themselves as a calf jumps over them in the bullring after the 4th day of the running of the bulls at the San Fermin Festival in Pamplona. (Alvaro Barrientos / Associated Press)

A participant falls next to fighting bulls from the Nunez del Cuvillo bull ranch during 5th day of the running of the bulls. (Alvaro Barrientos / Associated Press) Red scarves are held in the air to celebrate the 'Chupinazo' (start rocket) to mark the kickoff at noon sharp of the San Fermin Festival. (JOSE JORDAN / AFP / Getty Images)

Clockwise from top, revelers protect themselves as a calf jumps over them in the bullring after the fourth day of the running of the bulls at the San Fermin festival in Pamplona. A participant falls next to fighting bulls from the Nunez del Cuvillo ranch during fifth day of the running of the bulls. Red scarves are held in the air to celebrate the "chupinazo" (start rocket) to mark the kickoff of the San Fermin festival. (Alvaro Barrientos / Associated Press: Jose Jordan / AFP / Getty Images)

Some animal rights activists say the events are cruel and cause unnecessary harm to the bulls for the sake of human entertainment. But aficionados and bullfight promoters say the bull is a key part of the San Fermin tradition that needs to be preserved.

Bullfights are protected under Spain’s constitution as part of the country’s cultural heritage.

"Mozos," or runners, try to avoid the bulls during the traditional San Fermin bull run as they arrive to the bullring in Pamplona, Spain (Oihane H./ EPA / Shutterstock)

Falls or trampling by the bulls cause most injuries along the route.

Spanish bullfighter Lopez Simon needs assistance after falling during bullfight. (Jim Hollander /EPA / Shutterstock) A man is tossed by a bull as he tests his skills, or lack thereof, in getting close to the animal after the morning's running of the bulls in Pamplona. (Jim Hollander /EPA / Shutterstock)

People line the streets for the festivities of the San Fermin Festival in northern Spain. (Jim Hollander /EPA / Shutterstock) Street musicians play along the narrow streets in Pamplona. (Alvaro Barrientos / Associated Press)

Clockwise from top left, Spanish bullfighter Lopez Simon needs assistance after falling during a bullfight. A man is tossed by a bull as he tests his skills, or lack thereof, in getting close to the animal after the morning's running of the bulls. Street musicians play along the narrow streets in Pamplona. People line the streets for the festivities of the San Fermin festival in northern Spain.

The San Fermin festival in Pamplona attracts around 1 million visitors every year to the northern Spanish city of nearly 200,000. (Villar Lopez / EPA / Shutterstock)